OTTAWA — Prime Minister Justin Trudeau went on the attack in the House of Commons on Tuesday, accusing NDP Leader Jagmeet Singh of being willing to risk thousands of jobs by appearing to withdraw support for a massive B.C. liquefied natural gas project.

Trudeau’s comments come as both parties jockey for credibility on their environmental plans, with Parliament set to debate two competing motions this week on whether to declare a national climate emergency, both designed to expose the weaknesses of their rivals’ plans.

“Yesterday, the leader of the NDP flip-flopped on the LNG Canada project,” Trudeau said in Question Period. “He is now opposed to the largest private investment in Canadian history, a project that has the support of the British Columbia NDP and Indigenous communities. This flip-flop goes against 10,000 good jobs for British Columbians.”

On Monday, Singh told reporters in Ottawa that he has concerns about LNG Canada’s $40-billion natural gas export facility in northern B.C. and the Coastal GasLink pipeline that would feed it. He said all resource development projects must align with Canada’s climate-change goals, respect Indigenous rights and create jobs. “At this point, there’s some concerns that I’ve raised, and (the project) has not satisfied all those criteria,” he said. The NDP did not respond to a request for further comment from the Post on Tuesday.

Singh had previously voiced support for the project, which also has the backing of B.C’s NDP government. In January, he told CTV’s Evan Solomon that “the vast majority of Indigenous elected bands and chiefs have all shown support and the consultation process was done in a very meaningful way.”

But last week, the Green Party won a Vancouver Island riding previously held by the NDP in a byelection campaign in which fracking emerged as a key issue. LNG Canada would export natural gas extracted by fracking. Since then, Singh has faced calls from NDP candidate and former MP Svend Robinson to take a stronger position against fracking and oil and gas development.

“The NDP is completely inconsistent in its approach not just on the economy, but on the environment now too,” Trudeau said in the House of Commons on Tuesday. He also pointed out that NDP MP Nathan Cullen, whose northern B.C. riding includes the area around Kitimat where the export facility would be located, has supported the project.

Cullen told the Post the NDP caucus will talk through the issue at a meeting on Wednesday.

Trudeau’s comments came in response to questions from Singh accusing the Liberals of not doing enough to fight climate change. “The fact is the Liberals have the same emission targets as the Conservatives,” he said. “Both of them love pipelines and both would exempt the biggest polluters from paying.”

He is now opposed to the largest private investment in Canadian history

Singh is calling on the government to support an NDP motion to declare a climate emergency, which will be debated on Wednesday in the House of Commons. The motion calls for more ambitious cuts to greenhouse gas emissions and an end to fossil-fuel subsidies, which the Liberals promised in 2015 but have yet to achieve.

But the motion also calls on the government to cancel the controversial Trans Mountain pipeline expansion, meaning the Liberals are unlikely to support it.

Meanwhile, the Liberals have put forward their own motion calling for a declaration of a national climate emergency that seems to target the Conservatives, who have yet to present their own plan to fight climate change. The Liberal motion, to be debated on Thursday, “requires… that Canada commit to meeting its national emissions target under the Paris Agreement and to making deeper reductions in line with the Agreement’s objective of holding global warming below two degrees Celsius and pursuing efforts to keep global warming below 1.5 degrees Celsius.”

In a recent interview on CTV’s Question Period, Conservative Leader Andrew Scheer would not commit to meeting the Paris targets, saying the Conservative plan — expected next month — will “give Canada the best possible shot” at meeting its targets without a carbon tax. Environment Minister Catherine McKenna said Tuesday she’s “really interested” to see how the Conservatives will respond to the Liberal motion.

Declaring a climate emergency is a largely symbolic gesture that requires no specific action, and a Conservative spokesperson referred to the motion as an empty gesture. “Heavy on rhetoric, light on results,” said Brock Harrison. “Under Justin Trudeau, Canada is falling further and further away from hitting its emissions targets.”